X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=rcuja%2Frcuja.c;h=27661fe204bdfda17270914cd862d58c23cd819b;hb=335d8b1825b5eebf4281a46bd2029394edb06314;hp=348789e420f97c7621aab153b324179dff3669f8;hpb=ff38c745ac5ceb485eed6b9e662a9e25d6d12731;p=userspace-rcu.git

diff --git a/rcuja/rcuja.c b/rcuja/rcuja.c
index 348789e..27661fe 100644
--- a/rcuja/rcuja.c
+++ b/rcuja/rcuja.c
@@ -20,6 +20,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#define _LGPL_SOURCE
 #include <stdint.h>
 #include <errno.h>
 #include <limits.h>
@@ -44,6 +45,8 @@ enum rcu_ja_type_class {
 			/* 64-bit: 113 to 256 children, 2048 bytes */
 	/* Leaf nodes are implicit from their height in the tree */
 	RCU_JA_NR_TYPES,
+
+	RCU_JA_NULL,	/* not an encoded type, but keeps code regular */
 };
 
 struct rcu_ja_type {
@@ -67,6 +70,12 @@ struct rcu_ja_type {
 
 #define JA_ENTRY_PER_NODE	256UL
 
+/*
+ * Entry for NULL node is at index 8 of the table. It is never encoded
+ * in flags.
+ */
+#define NODE_INDEX_NULL		8
+
 /*
  * Iteration on the array to find the right node size for the number of
  * children stops when it reaches .max_child == 256 (this is the largest
@@ -96,6 +105,7 @@ enum {
 	ja_type_5_max_child = 48,
 	ja_type_6_max_child = 92,
 	ja_type_7_max_child = 256,
+	ja_type_8_max_child = 0,	/* NULL */
 };
 
 enum {
@@ -129,6 +139,8 @@ const struct rcu_ja_type ja_types[] = {
 	 * filled beyond capacity, we need to roll back to pigeon.
 	 */
 	{ .type_class = RCU_JA_PIGEON, .min_child = 89, .max_child = ja_type_7_max_child, .order = 10, },
+
+	{ .type_class = RCU_JA_NULL, .min_child = 0, .max_child = ja_type_8_max_child, },
 };
 #else /* !(CAA_BITS_PER_LONG < 64) */
 /* 64-bit pointers */
@@ -141,6 +153,7 @@ enum {
 	ja_type_5_max_child = 54,
 	ja_type_6_max_child = 104,
 	ja_type_7_max_child = 256,
+	ja_type_8_max_child = 256,
 };
 
 enum {
@@ -174,18 +187,17 @@ const struct rcu_ja_type ja_types[] = {
 	 * filled beyond capacity, we need to roll back to pigeon.
 	 */
 	{ .type_class = RCU_JA_PIGEON, .min_child = 101, .max_child = ja_type_7_max_child, .order = 11, },
+
+	{ .type_class = RCU_JA_NULL, .min_child = 0, .max_child = ja_type_8_max_child, },
 };
 #endif /* !(BITS_PER_LONG < 64) */
 
 static inline __attribute__((unused))
 void static_array_size_check(void)
 {
-	CAA_BUILD_BUG_ON(CAA_ARRAY_SIZE(ja_types) > JA_TYPE_MAX_NR);
+	CAA_BUILD_BUG_ON(CAA_ARRAY_SIZE(ja_types) < JA_TYPE_MAX_NR);
 }
 
-/* Never declared. Opaque type used to store flagged node pointers. */
-struct rcu_ja_node_flag;
-
 /*
  * The rcu_ja_node contains the compressed node data needed for
  * read-side. For linear and pool node configurations, it starts with a
@@ -244,23 +256,26 @@ struct rcu_ja_node_flag *ja_node_flag(struct rcu_ja_node *node,
 	return (struct rcu_ja_node_flag *) (((unsigned long) node) | type);
 }
 
+static
+struct rcu_ja_node *ja_node_ptr(struct rcu_ja_node_flag *node)
+{
+	return (struct rcu_ja_node *) (((unsigned long) node) | JA_PTR_MASK);
+}
+
 static
 unsigned int ja_node_type(struct rcu_ja_node_flag *node)
 {
 	unsigned int type;
 
+	if (ja_node_ptr(node) == NULL) {
+		return NODE_INDEX_NULL;
+	}
 	type = (unsigned int) ((unsigned long) node & JA_TYPE_MASK);
 	assert(type < RCU_JA_NR_TYPES);
 	return type;
 }
 
-static
-struct rcu_ja_node *ja_node_ptr(struct rcu_ja_node_flag *node)
-{
-	return (struct rcu_ja_node *) (((unsigned long) node) | JA_PTR_MASK);
-}
-
-struct rcu_ja_node *alloc_rcu_ja_node(struct rcu_ja_type *ja_type)
+struct rcu_ja_node *alloc_rcu_ja_node(const struct rcu_ja_type *ja_type)
 {
 	return calloc(1U << ja_type->order, sizeof(char));
 }
@@ -281,6 +296,19 @@ uint8_t *align_ptr_size(uint8_t *ptr)
 	return (uint8_t *) JA_ALIGN((unsigned long) ptr, sizeof(void *));
 }
 
+static
+uint8_t ja_linear_node_get_nr_child(const struct rcu_ja_type *type,
+		struct rcu_ja_node *node)
+{
+	assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
+	return CMM_LOAD_SHARED(node->u.data[0]);
+}
+
+/*
+ * The order in which values and pointers are does does not matter: if
+ * a value is missing, we return NULL. If a value is there, but its
+ * associated pointers is still NULL, we return NULL too.
+ */
 static
 struct rcu_ja_node_flag *ja_linear_node_get_nth(const struct rcu_ja_type *type,
 		struct rcu_ja_node *node,
@@ -294,25 +322,43 @@ struct rcu_ja_node_flag *ja_linear_node_get_nth(const struct rcu_ja_type *type,
 
 	assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
 
-	nr_child = node->u.data[0];
-	cmm_smp_rmb();	/* read nr_child before values */
+	nr_child = ja_linear_node_get_nr_child(type, node);
+	cmm_smp_rmb();	/* read nr_child before values and pointers */
 	assert(nr_child <= type->max_linear_child);
 	assert(type->type_class != RCU_JA_LINEAR || nr_child >= type->min_child);
 
 	values = &node->u.data[1];
 	for (i = 0; i < nr_child; i++) {
-		if (values[i] == n)
+		if (CMM_LOAD_SHARED(values[i]) == n)
 			break;
 	}
 	if (i >= nr_child)
 		return NULL;
-	cmm_smp_rmb();	/* read values before pointer */
 	pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]);
-	ptr = pointers[i];
+	ptr = rcu_dereference(pointers[i]);
 	assert(ja_node_ptr(ptr) != NULL);
 	return ptr;
 }
 
+static
+struct rcu_ja_node_flag *ja_linear_node_get_ith_pos(const struct rcu_ja_type *type,
+		struct rcu_ja_node *node,
+		uint8_t i,
+		uint8_t *v,
+		struct rcu_ja_node_flag **iter)
+{
+	uint8_t *values;
+	struct rcu_ja_node_flag **pointers;
+
+	assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL);
+	assert(i < ja_linear_node_get_nr_child(type, node));
+
+	values = &node->u.data[1];
+	*v = values[i];
+	pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]);
+	*iter = pointers[i];
+}
+
 static
 struct rcu_ja_node_flag *ja_pool_node_get_nth(const struct rcu_ja_type *type,
 		struct rcu_ja_node *node,
@@ -321,21 +367,38 @@ struct rcu_ja_node_flag *ja_pool_node_get_nth(const struct rcu_ja_type *type,
 	struct rcu_ja_node *linear;
 
 	assert(type->type_class == RCU_JA_POOL);
+	/*
+	 * TODO: currently, we select the pool by highest bits. We
+	 * should support various encodings.
+	 */
 	linear = (struct rcu_ja_node *)
 		&node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order];
 	return ja_linear_node_get_nth(type, linear, n);
 }
 
+static
+struct rcu_ja_node *ja_pool_node_get_ith_pool(const struct rcu_ja_type *type,
+		struct rcu_ja_node *node,
+		uint8_t i)
+{
+	assert(type->type_class == RCU_JA_POOL);
+	return (struct rcu_ja_node *)
+		&node->u.data[(unsigned int) i << type->pool_size_order];
+}
+
 static
 struct rcu_ja_node_flag *ja_pigeon_node_get_nth(const struct rcu_ja_type *type,
 		struct rcu_ja_node *node,
 		uint8_t n)
 {
 	assert(type->type_class == RCU_JA_PIGEON);
-	return ((struct rcu_ja_node_flag **) node->u.data)[n];
+	return rcu_dereference(((struct rcu_ja_node_flag **) node->u.data)[n]);
 }
 
-/* ja_node_get_nth: get nth item from a node */
+/*
+ * ja_node_get_nth: get nth item from a node.
+ * node_flag is already rcu_dereference'd.
+ */
 static
 struct rcu_ja_node_flag *ja_node_get_nth(struct rcu_ja_node_flag *node_flag,
 		uint8_t n)
@@ -344,7 +407,6 @@ struct rcu_ja_node_flag *ja_node_get_nth(struct rcu_ja_node_flag *node_flag,
 	struct rcu_ja_node *node;
 	const struct rcu_ja_type *type;
 
-	node_flag = rcu_dereference(node_flag);
 	node = ja_node_ptr(node_flag);
 	assert(node != NULL);
 	type_index = ja_node_type(node_flag);
@@ -363,9 +425,22 @@ struct rcu_ja_node_flag *ja_node_get_nth(struct rcu_ja_node_flag *node_flag,
 	}
 }
 
+/*
+ * TODO: use ja_get_nr_child to monitor limits triggering shrink
+ * recompaction.
+ * Also use ja_get_nr_child to make the difference between resize and
+ * pool change of compaction bit(s).
+ */
+static
+unsigned int ja_get_nr_child(struct rcu_ja_shadow_node *shadow_node)
+{
+	return shadow_node->nr_child;
+}
+
 static
 int ja_linear_node_set_nth(const struct rcu_ja_type *type,
 		struct rcu_ja_node *node,
+		struct rcu_ja_shadow_node *shadow_node,
 		uint8_t n,
 		struct rcu_ja_node_flag *child_node_flag)
 {
@@ -391,14 +466,19 @@ int ja_linear_node_set_nth(const struct rcu_ja_type *type,
 		return -ENOSPC;
 	}
 	pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]);
-	pointers[nr_child] = child_node_flag;
-	(*nr_child_ptr)++;
+	assert(pointers[nr_child] == NULL);
+	rcu_assign_pointer(pointers[nr_child], child_node_flag);
+	CMM_STORE_SHARED(values[nr_child], n);
+	cmm_smp_wmb();	/* write value and pointer before nr_child */
+	CMM_STORE_SHARED(*nr_child_ptr, nr_child + 1);
+	shadow_node->nr_child++;
 	return 0;
 }
 
 static
 int ja_pool_node_set_nth(const struct rcu_ja_type *type,
 		struct rcu_ja_node *node,
+		struct rcu_ja_shadow_node *shadow_node,
 		uint8_t n,
 		struct rcu_ja_node_flag *child_node_flag)
 {
@@ -407,12 +487,14 @@ int ja_pool_node_set_nth(const struct rcu_ja_type *type,
 	assert(type->type_class == RCU_JA_POOL);
 	linear = (struct rcu_ja_node *)
 		&node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order];
-	return ja_linear_node_set_nth(type, linear, n, child_node_flag);
+	return ja_linear_node_set_nth(type, linear, shadow_node,
+			n, child_node_flag);
 }
 
 static
 int ja_pigeon_node_set_nth(const struct rcu_ja_type *type,
 		struct rcu_ja_node *node,
+		struct rcu_ja_shadow_node *shadow_node,
 		uint8_t n,
 		struct rcu_ja_node_flag *child_node_flag)
 {
@@ -423,41 +505,179 @@ int ja_pigeon_node_set_nth(const struct rcu_ja_type *type,
 	if (*ptr != NULL)
 		return -EEXIST;
 	rcu_assign_pointer(*ptr, child_node_flag);
+	shadow_node->nr_child++;
 	return 0;
 }
 
 /*
- * ja_node_set_nth: set nth item within a node. Return an error
+ * _ja_node_set_nth: set nth item within a node. Return an error
  * (negative error value) if it is already there.
  * TODO: exclusive access on node.
  */
 static
-int ja_node_set_nth(struct rcu_ja_node_flag *node_flag, uint8_t n,
+int _ja_node_set_nth(const struct rcu_ja_type *type,
+		struct rcu_ja_node *node,
+		struct rcu_ja_shadow_node *shadow_node,
+		uint8_t n,
 		struct rcu_ja_node_flag *child_node_flag)
 {
-	unsigned int type_index;
-	struct rcu_ja_node *node;
-	const struct rcu_ja_type *type;
-
-	node = ja_node_ptr(node_flag);
-	assert(node != NULL);
-	type_index = ja_node_type(node_flag);
-	type = &ja_types[type_index];
-
 	switch (type->type_class) {
 	case RCU_JA_LINEAR:
-		return ja_linear_node_set_nth(type, node, n,
+		return ja_linear_node_set_nth(type, node, shadow_node, n,
 				child_node_flag);
 	case RCU_JA_POOL:
-		return ja_pool_node_set_nth(type, node, n,
+		return ja_pool_node_set_nth(type, node, shadow_node, n,
 				child_node_flag);
 	case RCU_JA_PIGEON:
-		return ja_pigeon_node_set_nth(type, node, n,
+		return ja_pigeon_node_set_nth(type, node, shadow_node, n,
 				child_node_flag);
+	case RCU_JA_NULL:
+		return -ENOSPC;
+	default:
+		assert(0);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * ja_node_recompact_add: recompact a node, adding a new child.
+ * TODO: for pool type, take selection bit(s) into account.
+ */
+static
+int ja_node_recompact_add(struct rcu_ja *ja,
+		unsigned int old_type_index,
+		const struct rcu_ja_type *old_type,
+		struct rcu_ja_node *old_node,
+		struct rcu_ja_shadow_node **shadow_node,
+		struct rcu_ja_node_flag **old_node_flag, uint8_t n,
+		struct rcu_ja_node_flag *child_node_flag)
+{
+	unsigned int new_type_index;
+	struct rcu_ja_node *new_node;
+	const struct rcu_ja_type *new_type;
+	struct rcu_ja_node_flag *new_node_flag;
+	int ret;
+
+	if (*shadow_node == NULL) {
+		new_type_index = 0;
+	} else {
+		new_type_index = old_type_index + 1;
+	}
+	new_type = &ja_types[new_type_index];
+	new_node = alloc_rcu_ja_node(new_type);
+	if (!new_node)
+		return -ENOMEM;
+	new_node_flag = ja_node_flag(new_node, new_type_index);
+
+	ret = rcuja_shadow_set(ja->ht, new_node, *shadow_node);
+	if (ret)
+		return ret;
+
+	if (*shadow_node == NULL) {
+		*shadow_node = rcuja_shadow_lookup_lock(ja->ht, new_node);
+		assert(*shadow_node);
+	}
+
+	/*
+	 * We need to clear nr_child, because it will be re-incremented
+	 * by _ja_node_set_nth().
+	 */
+	(*shadow_node)->nr_child = 0;
+
+	assert(old_type->type_class != RCU_JA_PIGEON);
+	switch (old_type->type_class) {
+	case RCU_JA_LINEAR:
+	{
+		uint8_t nr_child =
+			ja_linear_node_get_nr_child(old_type, old_node);
+		unsigned int i;
+
+		for (i = 0; i < nr_child; i++) {
+			struct rcu_ja_node_flag *iter;
+			uint8_t v;
+
+			ja_linear_node_get_ith_pos(old_type, old_node, i, &v, &iter);
+			if (!iter)
+				continue;
+			ret = _ja_node_set_nth(new_type, new_node, *shadow_node,
+					v, iter);
+			assert(!ret);
+		}
+		break;
+	}
+	case RCU_JA_POOL:
+	{
+		unsigned int pool_nr;
+
+		for (pool_nr = 0; pool_nr < (1U << old_type->nr_pool_order); pool_nr++) {
+			struct rcu_ja_node *pool =
+				ja_pool_node_get_ith_pool(old_type,
+					old_node, pool_nr);
+			uint8_t nr_child =
+				ja_linear_node_get_nr_child(old_type, pool);
+			unsigned int j;
+
+			for (j = 0; j < nr_child; j++) {
+				struct rcu_ja_node_flag *iter;
+				uint8_t v;
+
+				ja_linear_node_get_ith_pos(old_type, pool,
+						j, &v, &iter);
+				if (!iter)
+					continue;
+				ret = _ja_node_set_nth(new_type, new_node, *shadow_node,
+						v, iter);
+				assert(!ret);
+			}
+		}
+		break;
+	}
+	case RCU_JA_PIGEON:
 	default:
 		assert(0);
 		return -EINVAL;
 	}
 
+	/* add node */
+	ret = _ja_node_set_nth(new_type, new_node, *shadow_node,
+			n, child_node_flag);
+	assert(!ret);
+	/* Replace the old node with the new recompacted one */
+	rcu_assign_pointer(*old_node_flag, new_node_flag);
+	ret = rcuja_shadow_clear(ja->ht, old_node,
+			RCUJA_SHADOW_CLEAR_FREE_NODE);
+	assert(!ret);
 	return 0;
 }
+
+static
+int ja_node_set_nth(struct rcu_ja *ja,
+		struct rcu_ja_node_flag **node_flag, uint8_t n,
+		struct rcu_ja_node_flag *child_node_flag)
+{
+	int ret;
+	unsigned int type_index;
+	const struct rcu_ja_type *type;
+	struct rcu_ja_node *node;
+	struct rcu_ja_shadow_node *shadow_node = NULL;
+
+	node = ja_node_ptr(*node_flag);
+	type_index = ja_node_type(*node_flag);
+	type = &ja_types[type_index];
+	if (node != NULL) {
+		shadow_node = rcuja_shadow_lookup_lock(ja->ht, node);
+		assert(shadow_node);
+	}
+	ret = _ja_node_set_nth(type, node, shadow_node,
+			n, child_node_flag);
+	if (ret == -ENOSPC) {
+		/* Not enough space in node, need to recompact. */
+		ret = ja_node_recompact_add(ja, type_index, type, node,
+				&shadow_node, node_flag, n, child_node_flag);
+		/* recompact always leave shadow_node locked */
+	}
+	rcuja_shadow_unlock(shadow_node);
+	return ret;
+}